// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_SOCKET_UNIX_DOMAIN_SERVER_SOCKET_POSIX_H_
#define NET_SOCKET_UNIX_DOMAIN_SERVER_SOCKET_POSIX_H_

#include <stdint.h>
#include <sys/types.h>

#include <memory>
#include <string>

#include "base/callback.h"
#include "base/macros.h"
#include "net/base/net_export.h"
#include "net/socket/server_socket.h"
#include "net/socket/socket_descriptor.h"

namespace net {

class SocketPosix;

// Unix Domain Server Socket Implementation. Supports abstract namespaces on
// Linux and Android.
class NET_EXPORT UnixDomainServerSocket : public ServerSocket {
public:
    // Credentials of a peer process connected to the socket.
    struct NET_EXPORT Credentials {
#if defined(OS_LINUX) || defined(OS_ANDROID)
        // Linux/Android API provides more information about the connected peer
        // than Windows/OS X. It's useful for permission-based authorization on
        // Android.
        pid_t process_id;
#endif
        uid_t user_id;
        gid_t group_id;
    };

    // Callback that returns whether the already connected client, identified by
    // its credentials, is allowed to keep the connection open. Note that
    // the socket is closed immediately in case the callback returns false.
    typedef base::Callback<bool(const Credentials&)> AuthCallback;

    UnixDomainServerSocket(const AuthCallback& auth_callack,
        bool use_abstract_namespace);
    ~UnixDomainServerSocket() override;

    // Gets credentials of peer to check permissions.
    static bool GetPeerCredentials(SocketDescriptor socket_fd,
        Credentials* credentials);

    // ServerSocket implementation.
    int Listen(const IPEndPoint& address, int backlog) override;
    int ListenWithAddressAndPort(const std::string& address_string,
        uint16_t port,
        int backlog) override;
    int GetLocalAddress(IPEndPoint* address) const override;
    int Accept(std::unique_ptr<StreamSocket>* socket,
        const CompletionCallback& callback) override;

    // Creates a server socket, binds it to the specified |socket_path| and
    // starts listening for incoming connections with the specified |backlog|.
    int BindAndListen(const std::string& socket_path, int backlog);

    // Accepts an incoming connection on |listen_socket_|, but passes back
    // a raw SocketDescriptor instead of a StreamSocket.
    int AcceptSocketDescriptor(SocketDescriptor* socket_descriptor,
        const CompletionCallback& callback);

private:
    // A callback to wrap the setting of the out-parameter to Accept().
    // This allows the internal machinery of that call to be implemented in
    // a manner that's agnostic to the caller's desired output.
    typedef base::Callback<void(std::unique_ptr<SocketPosix>)> SetterCallback;

    int DoAccept(const SetterCallback& setter_callback,
        const CompletionCallback& callback);
    void AcceptCompleted(const SetterCallback& setter_callback,
        const CompletionCallback& callback,
        int rv);
    bool AuthenticateAndGetStreamSocket(const SetterCallback& setter_callback);

    std::unique_ptr<SocketPosix> listen_socket_;
    const AuthCallback auth_callback_;
    const bool use_abstract_namespace_;

    std::unique_ptr<SocketPosix> accept_socket_;

    DISALLOW_COPY_AND_ASSIGN(UnixDomainServerSocket);
};

} // namespace net

#endif // NET_SOCKET_UNIX_DOMAIN_SERVER_SOCKET_POSIX_H_
